Embodiments herein relate to connection establishment in a cellular wireless communication system that operates according to a 3rd generation partnership project (3GPP) specification, such as universal mobile telecommunications system (UMTS), long term evolution (LTE) and other radio access technologies wherein connection establishment is handled in a similar manner as in UMTS and LTE. When a wireless communication device (often denoted user equipment or UE) intends to initiate a voice call, initiate a data session or respond to a paging transmission, an early step is to request a radio resource control (RRC) connection. The normal procedure, e.g. as described in 3GPP technical specifications TS 36.331: 5.3.3 and TS 25.331: 8.1.3, is to make this request towards the radio base station of the cell the wireless communication device is currently camping on (i.e. tuned to a control channel of the cell). This is performed by transmitting an RRCConnectionRequest message to the radio base station that provides the control channel of the cell.
After having sent the RRCConnectionRequest, the wireless communication device awaits a response. The response from a radio base station may be an RRCConnectionSetup message that has an effect that the wireless communication device is granted an RRC connection and should use configuration information that is comprised in the RRCConnectionSetup message. The response from the radio base station may alternatively be an RRCConnectionReject message that has an effect that the wireless communication device is not granted an RRC connection. Depending on e.g. the load of the cell, the time for the wireless communication device to wait for the response from the cell (i.e. the radio base station) may vary. The cell indicates the maximum time to wait for a response by transmitting this information in system information broadcasted, in system information blocks (SIB) from the cell.
As can be readily appreciated, the response time will impact the user experience when initiating a connection. For example, the user will experience a delay when the response time is significant, e.g. for LTE the maximum response time can be up to 2 seconds and for wideband code division multiple access (WCDMA) radio access (used in UMTS) the maximum time is even longer-up to 8 seconds. With the increasing number of connected wireless communication devices in 2nd, 3rd and 4th generation (2G, 3G and 4G) 3GPP systems and anticipated huge increase in number of connected devices when 5th generation (5G) 3GPP systems are implemented, there is a high probability of long response times. Consequently, there is a gain in reducing the delay when a wireless communication device is initiating a network connection.
A problem with existing solutions is that the wireless communication device will normally request an RRC connection towards the cell on which the wireless communication device is camped on (denoted current or serving cell), without considering the maximum time the wireless communication device may have to wait for a response. If the maximum time to wait for a response is high for the current cell and significantly lower for a neighbour cell with sufficient signal quality of same or different frequency or radio access technology (RAT), there may be a significant loss, in terms of increased delay for the connection setup.